A reactor is one of the parts of a circuit that operates so as to raise and lower a voltage. For example, Patent Document 1 discloses a reactor used in a converter that is mounted in a vehicle such as a hybrid automobile. This reactor includes a coil, an annular magnetic core on which the coil is disposed, a case for housing an assembly constituted by the coil and the magnetic core, and sealing resin that fills the case. This reactor is generally used while fixed to a cooling base in order to cool the coil and the like that generate heat when power is supplied.
The above case is typically a die cast part made of aluminum, and is fixed to the cooling base and used as a heat dissipation path for releasing heat from the coil and the like.